Temperature control apparatus

ABSTRACT

A temperature control apparatus including a temperature control head kept in contact with an electronic device as a testing object thermally, an electric heater attached to the temperature control head, a refrigerant passage formed within the temperature control head so as to run through inside thereof, a compressor which compresses refrigerant coming out of the temperature control head, a temperature sensor which detects a temperature of refrigerant on an outlet side of the compressor, a condenser which condenses refrigerant coming out of the compressor, a returning portion which returns refrigerant condensed by the condenser to the temperature control head, and a control portion which bypasses the condensed refrigerant to the intake side of the compressor by a predetermined quantity corresponding to an output of the temperature sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation-in-Part application of U.S. patent applicationSer. No. 11/405,423, filed Apr. 18, 2006, the entire contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a temperature control apparatus, andparticularly to a temperature control apparatus for controlling thetemperature of an electronic device at the time of test.

2. Description of the Related Art

Prior to shipment, performance test of an electronic device, forexample, a semiconductor chip needs to be carried out at a roomtemperature or a higher temperature or a lower temperature. When theperformance test of a semiconductor chip is carried out at a roomtemperature under a rated current, heat is generated inside thesemiconductor chip by this current so that the temperature of the chipis raised more than the room temperature. Thus, the semiconductor chipneeds to be cooled appropriately to maintain the temperature at the roomtemperature. When the semiconductor chip is heated with a heater or thelike in case of high temperature test, it needs to be cooledappropriately in order to prevent the temperature from being raised morethan a setting temperature. These cases of cooling are carried out witha temperature setting head loaded with a semiconductor chip connected toa predetermined cooling system.

As a conventional temperature control apparatus, a temperature controlapparatus disclosed in, for example, U.S. Pat. No. 6,668,570 has beenknown. This conventional apparatus, as shown in FIG. 1 of this patentdocument, executes temperature control of an electronic device 10 by athermal head 14 which combines a passage 36 in which refrigerant flowswith an electric heater 30 in contact with the electronic device 10. Ina cooling system using the thermal head 14 having such a structure, heatis generated from the electronic device 10 and the heater 30 and thisheat is absorbed by the cooling system. Therefore, when the amount ofheat generated from the thermal head increases at the time of hightemperature test, for example, the quantity of heat absorbed byrefrigerant in the thermal head 14 increases so that the temperature ofrefrigerant supplied to a compressor 32 rises. As a result, thetemperature in the compressor 32 is raised by heat generated thereinwhen refrigerant is compressed and if this temperature exceeds a settingmaximum temperature of the compressor 32, a large thermal stress isapplied to components inside the compressor 32, so that the compressor32 may be possibly damaged. Therefore, the quantity of heat generatedfrom the heater 14 needs to be controlled strictly in order to preventthis serious phenomenon. This leads to increase in cost of the entiretemperature control apparatus and a temperature controllable rangebetween the lower limit and upper limit of the temperature controlnarrows, thereby limiting an electronic device which can be tested toparticular ones.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided atemperature control apparatus comprising: a temperature control headkept in contact with an electronic device as a testing object thermally;an electric heater attached to the temperature control head; arefrigerant passage formed within the temperature control head so as torun through inside thereof; a compressor which compresses refrigerantcoming out of the temperature control head; a temperature sensor whichdetects a temperature of the compressor; a condenser which condensesrefrigerant coming out of the compressor; a returning portion whichreturns refrigerant condensed by the condenser to the temperaturecontrol head; and a control portion which bypasses the refrigerantcondensed by the condenser to an intake side of the compressor by apredetermined quantity corresponding to an output of the temperaturesensor.

According to another aspect of the present invention, there is provideda temperature control apparatus comprising: a temperature control headkept in contact with an electronic device as a testing object thermally;an electric heater attached to the temperature control head; arefrigerant passage formed within the temperature control head so as torun through inside thereof; a first temperature sensor which detects atemperature of the electronic device; a compressor which compressesrefrigerant coming out of the temperature control head; a secondtemperature sensor which detects a temperature of the compressor; acondenser which condenses refrigerant coming out of the compressor; areturning portion which returns refrigerant condensed by the condenserto the temperature control head; and a control portion which controlsthe temperature of the electronic device by controlling the quantity ofelectricity supplied to the electric heater and the quantity ofrefrigerant flowing through the refrigerant passage corresponding to anoutput of the first temperature sensor and controls the quantity of thecondensed refrigerant bypassed to the intake side of the compressorcorresponding to an output of the second temperature sensor.

According to further aspect of the present invention, there is providedwith a temperature control apparatus comprising: a temperature controlhead kept in contact with an electronic device as a testing objectthermally; an electric heater attached to the temperature control head;a refrigerant passage formed within the temperature control head so asto run through refrigerant inside thereof; a first temperature sensorwhich detects a temperature of the electronic device; a compressor whichcompresses refrigerant coming out of the temperature control head; asecond temperature sensor which detects a temperature of refrigerant onthe outlet side of the compressor; a condenser which condensesrefrigerant coming out of the compressor; a returning portion whichreturns refrigerant condensed by the condenser to the temperaturecontrol head; a bypass portion including first and second bypasspassages connected in parallel to each other for returning therefrigerant condensed by the condenser to the compressor by bypassingthe temperature control head; a first control portion which controls thetemperature of the electronic device by controlling the quantity ofelectricity of the electric heater, the quantity of refrigerant flowingthrough the first bypass passage and the quantity of refrigerant flowingthrough the refrigerant passage in the temperature control headcorresponding to an output of the first temperature sensor; and a secondcontrol portion which controls a temperature of the refrigerant on theintake side of the compressor by controlling the quantity of refrigerantflowing through the second bypass passage corresponding to the output ofthe second temperature sensor.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagram schematically showing a structure of a coolingcircuit of a temperature control apparatus of an electronic deviceincluding a compressor protection section according to an embodiment ofthe present invention;

FIG. 2 is a structure diagram showing a concrete structure of theembodiment shown in FIG. 1;

FIG. 3 is a flow chart for explaining the temperature control operationof this embodiment; and

FIG. 4 is a flow chart for explaining the protective operation of thecooling circuit according to this embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the present invention will be described indetail with reference to the accompanying drawings.

Referring to FIG. 1, an evaporator 13 is provided within a temperaturecontrol head 12 with which an electronic device 11 as a testing objectsuch as a semiconductor chip is kept in contact thermally. An electricheater described later is attached to this head 12 and a refrigerantpassage 14 a in which refrigerant flows through is formed within theevaporator 13. The evaporator 13 is connected to a cooling circuitincluding a pipe 15 serving as a passage of refrigerant. An expansionvalve 16 is connected to a refrigerant intake side of the evaporator 13and an outlet side thereof is connected to a compressor 18 through anaccumulator 17. The pressure of refrigerant on the intake side of theexpansion valve 16 is high while the pressure of refrigerant in thedownstream of the evaporator 13 on the outlet is low.

After passing the temperature control head 12, low pressure gaseousrefrigerant is collected in the accumulator 17 and then fed to andcompressed in the compressor 18. High pressure gaseous refrigerantcompressed by this compressor 18 is condensed by a condenser 19 on anext step using a fan 20 to form mist-like refrigerant. The mist-likerefrigerant formed in the condenser 19 is a mixture of gaseousrefrigerant and condensed refrigerant particles or small liquidparticles of refrigerant. The condensed mist-like refrigerant isreturned to the expansion valve 16 through the pipe 15 and furtherreturned to the accumulator 17 through a bypass including anelectromagnetic valve 21 and a capillary tube 22. Further, the outletside of the compressor 18 and intake side of the expansion valve 16 areconnected by a bypass line 23 via an electromagnetic valve 24, so thatthe gaseous refrigerant of high-temperature and high-pressure is mixedwith the mist-like refrigerant flowing through the pipe 15 at the inletside of the expansion valve 16.

The cooling system having such a structure includes a first temperaturesensor T1 for detecting the temperature of the electronic device 11 inthe temperature control head 12 and a second temperature sensor T2 fordetecting the temperature of the compressor 18. In the case of FIG. 1,the sensor T2 is set at the outlet side of the compressor for measuringthe temperature of the refrigerant on the outlet side of the compressor18. The sensor T2 may be provided at the inlet side of the compressor 18for measuring the temperature of the refrigerant supplied to thecompressor 18 or may be provided at the inside of the compressor 18 asthe temperature of the compressor 18. It further includes a systemcontroller being described later (not shown in FIG. 1) which executes,for example, PID control as a control portion for controlling thetemperature of the electronic device 11 by controlling the quantity ofcurrent supplied to the electric heater and the quantity of refrigerantflowing through the refrigerant passage 14a corresponding to an outputof the first temperature sensor T1 and controlling the quantity of thecondensed refrigerant bypassing to the intake side of the compressor 18through the capillary tube 22 corresponding to an output of the secondtemperature sensor T2. The amount of bypassed refrigerant through thebypass line 23 from the outlet side of the compressor 18 to the inletside of the expansion valve 16 is controlled to by constant by openingthe electromagnetic valve 24 at a fixed opening position determined inaccordance with a specification of the electronic device 11 to betested. The detailed explanation of the valve control will be describedlater.

The cooling system shown in FIG. 1 may be provided with a drier DR, ahigh-pressure gauge G1, a high-pressure pressure switch P1, anelectromagnetic valve S, a service port SP, a ball valve V, a lowpressure gauge G2, a low-pressure pressure switch P2 and the likecorresponding to each purpose.

Hereinafter, the concrete structure of the cooling system shown in FIG.1 will be described with reference to FIG. 2.

The same reference numerals are attached to components corresponding tothose of FIG. 1. The temperature control head 12 is constructed bycombining the evaporator 13 having plural refrigerant passages 14 a andan electric heater 14 b. An electronic device or a semiconductor chip 11is pressed to the bottom face of the temperature control head 12 througha high-heat conductive member 12 a. A plurality of solder ball terminals11 a are formed on the bottom face of the semiconductor chip 11 and thesemiconductor chip 11 is connected to a connecting terminal provided ona socket 10 s through this solder ball terminal 11 a and furtherconnected to an outside test unit (not shown) so as to perform apredetermined test. A probe T1P of the temperature sensor T1 is kept incontact with the semiconductor chip 11 and a detection output of thetemperature sensor T1 is supplied to a system controller 31 for PIDcontrol. The electric heater 14 b provided on the temperature controlhead 12 is driven by a heater driver 14 bD under a control of the systemcontroller 31. A computer such as a micro-processor may be used as thesystem controller 31 in place of the PID controller.

The plurality of refrigerant passages 14 a formed within the evaporator13 are connected to the refrigerant pipe 15 on the intake side and therefrigerant pipe 15 on the outlet side. The refrigerant pipe 15connected to the outlet side of the temperature control head 12 isconnected to the compressor 18 through the accumulator 17. A probe T2Pof another temperature sensor T2 is installed on the refrigerant pipe 15on the outlet side of this compressor 18 in the present embodiment so asto detect the temperature of refrigerant on the outlet side of thecompressor 18. As above-mentioned, the probe T2P of the sensor T2 may beprovided at another place such as on the inlet side of inside of thecompressor 18. A detection output of this temperature sensor T2 issupplied to the system controller 31.

The refrigerant pipe 15 connected to the outlet side of the compressor18 is coupled with the intake side of the condenser 19. This condenser19 is a heat radiator and heat of refrigerant is radiated by blowing airto the radiator 19 with the fan 20 to condense gaseous refrigerant tomist-like refrigerant. The refrigerant pipe 15 connected to the outletside of the condenser 19 is branched to a first branch pipe 15A and asecond branch pipe 15B in succession. These first and second branchpipes 15A, 15B communicate with the refrigerant pipe 15 connected to theintake side of the accumulator 17 through electromagnetic valves 15AV,15BV, respectively. These electromagnetic valves 15AV, 15BV areopened/closed by the system controller 31 under each predeterminedcondition, which will be described later.

The refrigerant pipe 15 connected to the outlet side of the condenser 19is connected to the intake side of the electronic expansion valve 16provided on the intake side of evaporator 13.

Further, in the embodiment shown in FIGS. 1 and 2, a bypass line 23 isprovided from the outlet side of the compressor 18 to the inlet side ofthe expansion valve 16 for bypassing the condenser 19. Anelectromagnetic valve 24 is provided on the bypass line 23. The bypassline 23 is connected between the refrigerant pipe 15 at the outlet sideof the compressor 18 to another refrigerant pipe 15 connected from theoutlet side of the condenser 19 to the inlet side of the expansion valve16 via the electromagnetic valve 24, thereby bypassing the condenser 19.In the case of FIG. 2, the outlet side of the electromagnetic valve 24is connected at a point on the pipe 15 provided between the twobypassing points of the bypass lines 15A and 15B. Further, the outletside of the electromagnetic valve 24 may be connected preferably at aposition on the pipe line 15 between the bypassing point of the bypassline 15B and the expansion valve 16. The electromagnetic valve 24 is setat a predetermined open position according to a control signal from thesystem controller 31.

Next, the operation of the cooling system having such a structure shownin FIG. 2 will be described with reference to FIGS. 3 and 4. If theperformance test of the electronic device 11 is carried out at apredetermined temperature higher than the room temperature, a user setsup a lower limit value STL of a setting temperature range in the systemcontroller 31. In this case, a temperature DT of the temperature controlhead 12 is equal to the room temperature and a temperature detected bythe temperature sensor T1 through the probe T1P is low when thetemperature control is started. Thus, a result of determination turns toYES in initial step S1 of FIG. 3 (DT<STL?) and the control proceeds tostep S2. As a consequence, an instruction of “CLOSE” is sent from thesystem controller 31 to the expansion valve 16 so that no refrigerantflows to the evaporator 13 and the valve 15BV turns to “OPEN” to allowrefrigerant to pass through the bypass passage 15B. At the same time,the heater driver 14 bB is driven to supply electricity to the electricheater 14 b, so that the temperature control head 12 is heated up to thetest temperature.

At this time, the electromagnetic valve 24 is set at an open state witha predetermined open degree and the gaseous refrigerant ofhigh-temperature and high-pressure from the compressor 18 is supplied tothe inlet side of the expansion valve 16. However, since the expansionvalve 16 is set at the closed state, this refrigerant bypassed thecondenser 19 is not supplied to the expansion valve 16 but is returnedthrough the bypass line 15B. At this time, the electronic device 11being tested is not positioned in the temperature control head 12. Thedevice 11 is held at the high testing temperature at a waiting position(not shown). The open degree of the electromagnetic valve 24 is set at apredetermined value when the device test is started so that thetemperature of the temperature control head 12 is held within apredetermined range in response to the heat generated during theelectronic device 11 is tested and the ambient temperature of the head12.

When the temperature DT of the temperature control head 12 exceeds thelower setting temperature STL, a result of determination in step S1becomes at NO, the electronic device 11 being tested is put in thetemperature control head 12, and the performance test of the device 11is executed. During the test, a predetermined test current flows throughthe device 11 and heat will be generated from the device 11, and thecontrol proceeds to step S3. Here, whether or not the temperature DT ofthe head 12 or the electronic device 11 detected by the temperaturesensor T1 exceeds the upper limit value STH of the test temperaturerange (DT>STH?) is determined. If the result is NO, the control proceedsto step S4, in which an instruction of “CLOSE” continues to be given tothe electromagnetic expansion valve 16 from the system controller 31 anda condition in which refrigerant is blocked from flowing to theevaporator 13 is maintained and the valve 15BV turns to “OPEN” so thatrefrigerant continues to pass through the bypass passage 15B. At thesame time, the heater driver 14 bD is stopped to drive the electricheater 14 b which is turned to non-driven state, thereby stoppingheating of the electronic device 11. On the other hand, a test currentis continued to be supplied to the electronic device 11 andpredetermined amount of heat is generated according to the test current.

On the other hand, if the temperature of the electronic device 11 risestoo much in the condition of step S3 (DT>STH? is YES), the controlproceeds to step S5, in which an instruction “OPEN” is supplied from thesystem controller 31 to the electromagnetic expansion valve 16 and themist-like refrigerant begins to flow into the evaporator 13. At the sametime, the valve 15BV turns to “CLOSE” so that refrigerant is blockedfrom passing the bypass passage 15B. At this time, the drive conditionof the heat driver 14 bD is released so that no current is supplied tothe electric heater 14 b and the heating of the electronic device 11 bythe heater 14 b is stopped, except for the heating by the interior heatgenerated from the electronic device 11. As a result, the electronicdevice 11 is cooled by absorption of heat when the mist-like refrigerantflowing through the evaporator 13 is evaporated and the temperature DTfalls to the lower setting temperature STL. In this condition, since theelectromagnetic valve 24 is set to an open state with a predeterminedopen degree, the gaseous refrigerant of high-temperature andhigh-pressure is supplied directly to the inlet side of the expansionvalve from the outlet side of the compressor 18 so that the gaseousrefrigerant is mixed with the mist-like refrigerant in the pipe 15. As aresult, the temperature of the mist-like refrigerant supplied to thetemperature control head 12 from the expansion valve 16 is high comparedwith a case in which no gaseous refrigerant is supplied from the pipe 23via the electromagnetic valve 24. Therefore, when a high-temperaturetest of 100° C., for example, is being executed, it is possible tomaintain the test temperature of 100° C. by supplying the hightemperature gaseous refrigerant from the valve 24.

When DT<STL is obtained, the control is YES in step S1 so that the sametemperature control action is maintained between the lower and uppertemperature setting ranges STL and STH.

As for the control of the electric heater 14 b and the expansion valve16, software control by a computer can be executed instead of hardwarecontrol by the system controller 31 by PID.

When the performance test of the electronic device 11 is executed at ahigh temperature higher than the room temperature in the embodiment ofFIG. 2, the user sets the system controller 31 so that the heater 14 bis driven by the heater driver 14 bD to generate heat. In the same time,the temperature of the temperature control head 12 is set to be high sothat the electronic device 11 being tested is heated at a testtemperature, when the test is started. In the embodiment, theelectromagnetic valve 24 is set to be open when the high-temperaturetest is started. In this condition, the electromagnetic valves 15AV,15BV are closed and the expansion valve 16 is set to be open.

When the device performance test is started, the test current issupplied to the electronic device 11, and the high temperature gaseousrefrigerant delivered at the outlet side of the compressor 18 issupplied to the pipe 15 at the inlet side of the expansion valve 16 viathe electromagnetic valve 24 in the bypass line 23. Low temperaturemist-like refrigerant flowing in the pipe 15 from the condenser 19 ismixed with the high temperature gaseous refrigerant flowing into thepipe 15 from the pipe 23 and the mixed refrigerant is supplied to theexpansion valv 16. Thus, after the test is started, the temperature ofthe refrigerant at the inlet side of the expansion valve 16 raisesrapidly in the case of the embodiment shown in FIG. 2. The pressure ofthe refrigerant is lowered at the outlet side of the expansion valve 16and the low pressure mist-like refrigerant is supplied to the evaporator13 of the temperature control head 12. The mist-like refrigerant isevaporated in the evaporator 13 to regulate and maintain the temperatureof the electronic device 11 at the test temperature. The temperature inthe temperature control head 12 is mainly varied by the heat generatedfrom the interior of the electronic device 11 during the performancetest is executed. Therefore, the temperature in the head 12 is mainlycontrolled so as to maintain the temperature in the head 12 at the testtemperature in response to the temperature change caused by the heatgenerated from the device 11 under test by appropriately absorbing thisheat with the evaporated refrigerant.

Since the maximum rated current being supplied to the electronic device11 during the performance test thereof is known, the maximum amount ofheat generated from the device can be estimated. Further, even if theelectromagnetic valve 24 is set at a constant open state, it is possibleto maintain the temperature of the device 11 within a predeterminedobjective temperature range by the refrigerant supplied from theexpansion valve 16 so that the refrigerant can absorb the fluctuation ofthe heat generated from the device 11, by controlling the heater driver14 bD to supply corresponding current to the electric heater 14 b by thesystem controller 31 during the test is executed, In the embodimentshown in FIG. 2, as above-mentioned, the bypass line 15A including theelectromagnetic valve 15AV is important for protecting the compressor18. Thus, the high-temperature test for the electronic device 11 can beperformed with the electromagnetic valve 24 and the expansion valve 16are set at the open state during the execution of the test, therebyenabling the temperature control of the device 11 under test veryeasily.

When the test is being performed at a low temperature, at 25° C. nearthe room temperature, for example, the electric heater 14 b is notdriven and only the heat is generated from the device 11 during the testis performed. When the supply current to the device 11 during the testis small, it is not required to cool the device 11 since little heat isgenerated. When the supply current is large, much heat will be generatedfrom the device 11 and the temperature of the device 11 may be variedbeyond the set test temperature range of 25±3° C. When this is occurred,the electromagnetic valve 24 is closed so that the mist-like lowtemperature refrigerant from the condenser 19 is only supplied to thetemperature control head 12 from the expansion valve 16. When theexpansion valve 16 is set at the open state, a constant amount ofrefrigerant is supplied to the head 12. The refrigerant is the mist-likerefrigerant which is a mixture of the gaseous refrigerant and fineparticle liquid refrigerant. Therefore, when the high temperaturegaseous refrigerant from the valve 24 is mixed with the low-temperaturemist-like refrigerant, the component of the fine liquid particlerefrigerant in the mixture of the refrigerant decreases and the coolingability of the mixture refrigerant may be lowered in the temperaturecontrol head 12. On the contrary, when the electromagnetic valve 24 isclosed in the low-temperature test, the cooling ability will beincreased, since the component of the fine liquid particle increases.Therefore, even if the heat generated from the device 11 under testincreases abruptly, it is possible to absorb the heat effectively in thetemperature control head 12 so that the temperature of the device 11 maybe maintained near the test temperature of 25° C.

Next, the operation of preventing the compressor 18 from being destroyedby overheat will be described with reference to FIG. 4. When thetemperature control of the electronic device 11 is carried out withreference to FIG. 3, the refrigerant temperature RT in the pipe 15 onthe outlet side of the compressor 18 is detected by the probe T2P of thetemperature sensor T2 and sent to the system controller 31. Arefrigerant upper limit temperature PT is set up on the systemcontroller 31 in order to protect the compressor 18 and whether or notthis refrigerant temperature RT is over the set refrigerant upper limittemperature PT is determined in step S11.

When the refrigerant temperature RT is lower than the refrigerant upperlimit temperature PT, the result is NO and the control proceeds to stepS12, in which the electromagnetic valve 15AV on the refrigerant bypasspassage 15A is kept in “CLOSE”. At this time, the electromagnetic valve15BV on the other refrigerant bypass passage 15B can be opened or closedcorresponding to the temperature DT of the electronic device 11 asdescribed in FIG. 3.

When the refrigerant temperature RT on the outlet side of the compressor18 is higher than the upper limit temperature PT, a determination resultin step S11 is YES and the control proceeds to step S13. Theelectromagnetic valve 15AV is opened by a control of the systemcontroller 31 and refrigerant condensed and cooled by the condenser 19flows into the accumulator 17 through the bypass passage 15A. As aconsequence, the temperature RT of refrigerant supplied from theaccumulator 17 to the compressor 18 drops thereby preventing thecompressor 18 from being overheated.

Drop of the refrigerant temperature RT on the outlet side of thecompressor 18 by opening of the electromagnetic valve 15AV is continuedwhile the result is NO in step S14 (RT<PT?).

If the result is YES in step S14 (RT<PT?), the control proceeds to stepS12, in which the electromagnetic valve 15AV is closed under a controlof the system controller 31 so that bypass refrigerant flowing into theaccumulator 17 is vanished. As a consequence, the refrigeranttemperature RT on the outlet side of the compressor 18 begins to riseagain. Control of the refrigerant temperature on the outlet side of thecompressor 18 by opening/closing of the electromagnetic valve 15AV canbe carried out without affecting the temperature control operation ofthe electronic device 11 so much.

According to this embodiment, as described above, this temperature doesnot exceed the setting maximum temperature of the compressor 18 even ifthe quantity of heat generated from the heater 14 b increases in a hightemperature test so that the temperature of refrigerant supplied to thecompressor 18 rises. Thus, components in the compressor 18 are protectedfrom a large thermal stress, thereby protecting the compressor 18 from adamage. Thus, it is possible to maintain effectively the temperature ofthe electronic device 11 under test at the objective test temperature,even if the test temperature is set at a high temperature or at a lowtemperature.

Therefore, the quantity of heat generated from the heater 14 b does notneed to be carried out strictly, cost of the entire temperature controlapparatus can be suppressed to a low level, a temperature controllablerange between the lower limit and upper limit of the temperature controlcan be secured widely and an electronic device which can be tested isnot restricted to any particular type.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A temperature control apparatus comprising: a temperature controlhead kept in contact with an electronic device as a testing objectthermally; an electric heater attached to the temperature control head;a refrigerant passage formed within the temperature control head so asto run through refrigerant inside thereof; a compressor which compressesthe refrigerant coming out of the temperature control head; atemperature sensor which detects a temperature of refrigerant on anoutlet side of the compressor; a condenser which condenses refrigerantcoming out of the compressor; a returning portion which returnsrefrigerant condensed by the condenser to the temperature control head;and a control portion which bypasses the condensed refrigerant to anintake side of the compressor by a predetermined quantity correspondingto an output of the temperature sensor.
 2. The temperature controlapparatus according to claim 1, further comprising a bypass line forsupplying the refrigerant at the outlet side of the compressor to thetemperature control head by bypassing the condenser.
 3. The temperaturecontrol apparatus according to claim 2, wherein the bypass line includesa control valve for controlling flow rate of the refrigerant from thecompressor.
 4. The temperature control apparatus according to claim 1,wherein the control portion includes means for bypassing the refrigerantwhen an output temperature value of the temperature sensor exceeds theupper limit value of the temperature of refrigerant on the outlet sideof the compressor set preliminarily as a result of comparison of theoutput temperature value of the temperature sensor with the upper limitvalue of the refrigerant temperature.
 5. The temperature controlapparatus according to claim 4, wherein the control portion whichbypasses the refrigerant includes a bypass passage that communicates theoutlet side of the condenser to the intake side of the compressor andmeans for turning ON/OFF refrigerant flowing through the bypass passageby means of the control portion.
 6. The temperature control apparatusaccording to claim 1, wherein the control portion includes a systemcontroller for PID control.
 7. A temperature control apparatuscomprising: a temperature control head kept in contact with anelectronic device as a testing object thermally; an electric heaterattached to the temperature control head; a refrigerant passage formedwithin the temperature control head so as to run through refrigerantinside thereof; a first temperature sensor which detects a temperatureof the electronic device; a compressor which compresses refrigerantcoming out of the temperature control head; a second temperature sensorwhich detects a temperature of refrigerant on the outlet side of thecompressor; a condenser which condenses refrigerant coming out of thecompressor; a returning portion which returns refrigerant condensed bythe condenser to the temperature control head; and a control portionwhich controls the temperature of the electronic device by controllingthe quantity of electricity supplied to the electric heater and thequantity of refrigerant flowing through the refrigerant passagecorresponding to an output of the first temperature sensor and controlsthe quantity of condensed refrigerant bypassed to the inlet side of thecompressor according to an output of the second temperature sensor. 8.The temperature control apparatus according to claim 7, furthercomprising a bypass line for supplying the refrigerant at the outletside of the compressor to the temperature control head by bypassing thecondenser.
 9. The temperature control apparatus according to claim 8,wherein the bypass line includes a control valve for controlling flowrate of the refrigerant from the compressor.
 10. The temperature controlapparatus according to claim 7, wherein the control portion includesmeans for bypassing the refrigerant when an output temperature value ofthe second temperature sensor exceeds the upper limit value of thetemperature of refrigerant on the outlet side of the compressor setpreliminarily as a result of comparison of the output temperature valueof the second temperature sensor with the upper limit value of therefrigerant temperature.
 11. The temperature control apparatus accordingto claim 10, wherein the means for bypassing includes a bypass passagethat communicates the outlet side of the condenser to the intake side ofthe compressor and means for turning ON/OFF refrigerant flowing throughthe bypass passage by means of the control portion.
 12. The temperaturecontrol apparatus according to claim 7, wherein the control portionincludes a system controller for PID control.
 13. A temperature controlapparatus comprising: a temperature control head kept in contact with anelectronic device as a testing object thermally; an electric heaterattached to the temperature control head; a refrigerant passage formedwithin the temperature control head so as to run through refrigerantinside thereof; a first temperature sensor which detects a temperatureof the electronic device; a compressor which compresses refrigerantcoming out of the temperature control head; a second temperature sensorwhich detects a temperature of refrigerant on the outlet side of thecompressor; a condenser which condenses refrigerant coming out of thecompressor; a returning portion which returns refrigerant condensed bythe condenser to the temperature control head; a bypass portionincluding first and second bypass passages connected in parallel to eachother for returning the refrigerant condensed by the condenser to thecompressor by bypassing the temperature control head; a first controlportion which controls the temperature of the electronic device bycontrolling the quantity of electricity of the electric heater, thequantity of refrigerant flowing through the first bypass passage and thequantity of refrigerant flowing through the refrigerant passage in thetemperature control head corresponding to an output of the firsttemperature sensor; and a second control portion which controls thetemperature of the refrigerant on the intake side of the compressor bycontrolling the quantity of refrigerant flowing through the secondbypass passage corresponding to the output of the second temperaturesensor.
 14. The temperature control apparatus according to claim 13,wherein the second control portion includes means for bypassing therefrigerant to the second bypass passage when an output temperaturevalue of the second temperature sensor exceeds the upper limit value ofthe temperature of refrigerant on the outlet side of the compressor setpreliminarily as a result of comparison of the output temperature valueof the temperature sensor with the upper limit value of the refrigeranttemperature.
 15. The temperature control apparatus according to claim13, wherein the means for bypassing includes an electromagnetic valveprovided on the second bypass passage and means for turning ON/OFF therefrigerant flowing through the second bypass passage by means of theelectromagnetic valve.
 16. The temperature control apparatus accordingto claim 13, wherein at least one of the first and second controlportions includes a controller for PID control.
 17. The temperaturecontrol apparatus according to claim 13, further comprising a bypassline for supplying the refrigerant at the outlet side of the compressorto the temperature control head by bypassing the condenser.
 18. Thetemperature control apparatus according to claim 17, wherein the bypassline includes a control valve for controlling flow rate of therefrigerant from the compressor.